\documentclass{book}
\usepackage{tikz}
\usetikzlibrary{tikzmark, calc}
\usepackage{array}
\usepackage{multirow}
\setlength{\extrarowheight}{2pt}

\begin{document}
    \begin{tabular}{|c|c|c|}
        \hline
        foo & bar & baz \\
        \hline 
        \multicolumn{2}{|c|}{\tikzmark{smc}\hfill double\hfill\tikzmark{emc}} & B \\
        \hline
        C & D & \tikzmark{smr}\multirow{2}{*}{$\delta$}\tikzmark{smr} \\
        E & F & \\
        \hline
    \end{tabular}
    \begin{tikzpicture}[overlay,remember picture]
        \draw ($(pic cs:smc)-(\tabcolsep,3.6pt)$) -- ($(pic cs:emc)+(\tabcolsep,10.4pt)$);
        \draw ($(pic cs:smr)-(16pt,17.6pt)$) -- ($(pic cs:emr)+(-3.7pt,2.2pt)$);
    \end{tikzpicture}
\end{document}

enter image description here
